Displayed next to the hook should be the first harpoon he strapped to his arm (which looked freaking awesome), a Black Manta helmet, a bridle and saddle from his days of riding giant seahorses, a rod and reel from The Fisherman and bronzed baby shoes.

Time and Tide shows a bunch of items on the walls in the framing sequence.

Pictures of his family, including Vulko. Various hooks and swords. A periscope. The Key to the City Aquaman received when he first met Flash. Books, including The Atlantis Chronicles. A gun he took from Ocean Master. A skeleton of a sea monster. A stuffed sea monster head.

The Year One Annual also has a framing sequence set in the cave.

A diving helmet. A Hula skirt (that Mera wore). A giant feather. A trunk with clothes in it. A statue.

-- Hunk of coral and Jolly Roger flag from first supervillain case (vs. Captain Black Jack) More Fun Comics #74, the second Aquaman story and the first that can easily be "updated" to be part of the E-1/Post-Crisis version's career)

-- Pearls given as an honor by chief Keoki for defeating Black Jack (More Fun #75, first appearance of the Aquacave!)